This invention relates to inkjet printers, and in particular to a method and apparatus for flushing ink tubes in an inkjet printer.
Conventional inkjet printers have typically employed a self-contained printing cartridge, composed of a reservoir and printhead in one unit. Ink from the reservoir flows into a number of chambers in the printhead. The chambers are then quickly heated causing the ink to expel onto a printing media, for example, paper, acetate, cloth, etc. A separate printhead-cleaning device is utilized to clean the printhead by providing at least one wiper, over which the printhead passes, to wipe off any accumulated ink, ink residue or fibers remaining from the media being printed upon.
Over time inkjet printing has become more sophisticated, and now delivers the capability to print in any number of colors, complicated graphic designs, utilizes a vast number of different fonts, and is able to print photographs. As a result, later generation printers, especially large-format ones, consume more ink and utilize different ink compositions.
In order to accommodate higher ink consumption without having an operator change cartridges more often, the xe2x80x9call in onexe2x80x9d printing cartridge has evolved to a more complex ink delivery system. The system includes a printhead, an ink reservoir, a printhead cleaning device (collectively referred to as printing components) and a tube connecting the reservoir to the printhead. The ink reservoir is usually easily replaceable and typically holds a larger quantity of ink than the printing cartridge design.
The number of ink compositions available for use in ink jet printers has also increased in order to provide the number of colors and photographic quality desired by users. However, some new ink compositions are incompatible with previous ink compositions. For instance, installing an ink cartridge with a new ink composition, while an old ink is present in the tubing or printhead, may result in the new ink composition combining with the old ink composition to form a precipitate, clogging the tubing or the printhead. Also, other problems may occur when installing an ink cartridge with a new ink composition, while the old ink is still present in the tubing and printhead of the printer, if the properties of the new ink are altered. This can be an especially severe problem when the new ink has a different color than the previously used ink. Thus, until the old ink is purged, print quality generally suffers. In general, any time a new ink composition is to be used in place of a non-identical ink composition, a potential incompatibility issue is presented (e.g., different colors, densities, solvents, pigments, surfactants, etc.).
In order to provide larger quantities of ink and multiple compositions of ink, printer manufacturers offer multiple printheads supplied by multiple reservoirs. However, because it is impractical to supply every type of ink desired in a particular printer, users must still change inks with all the incompatibility problems mentioned above. In printers utilizing a reservoir separate from the printhead, it is desirable to be able to change inks without mixing a new ink with an old ink.
One solution to the problems associated with incompatible ink compositions is to change the printing components, i.e. the reservoir, printhead, printhead cleaner, and the associated tubing during each ink change. By example, a printer utilizing separate reservoirs and printheads causes the printheads to regularly dock into a refill station. The reservoirs then connect to their corresponding printheads through short tubes which are integral to each reservoir. When changing ink types, a user may then change the reservoirs and tubes as a single assembly and also change the printheads and printhead cleaning devices. This system has the advantage of replacing all parts that contact the ink, thus eliminating any possible mixing of old ink and new ink. This method has a disadvantage in that it cannot be used on higher throughput printers where the tubing is more permanently routed inside the printer and difficult to access.
Another solution is to provide as many tubes in the printer as desired ink compositions. For example, if the user contemplates using eight different compositions of ink, then eight tubes are required. However, if later in time, additional ink compositions are desired, more tubes need to be installed. Anticipating the number of ink compositions and providing room for the contemplated tubing is impractical.
Another solution is to clean or purge the tubes of the previously used ink. In higher throughput printers where the tubing is more permanently routed inside the printer and difficult to access, this operation requires some disassembly of the printer in order to flush the tubes with distilled water. This procedure requires some provision for collecting the used distilled water and also requires some training for the operator and some protection against ink spillage.
It is desirable then to perform purging operations automatically, in order to minimize user intervention. Information devices may be incorporated into the printing components which identify them to a processor in the printer. A proposal to incorporate a parameter memory into ink jet printheads can be found in the publication entitled xe2x80x9cStorage of Operating Parameters in Memory Integral with Print Headxe2x80x9d, Lonis, Xerox Disclosure Journal, Volume 8, No. 6, November/December 1983. The author discusses storage of operating parameters to be used by a printer for calibration purposes, including drop generator driver frequency, ink pressure and drop charging values.
Also of interest is U.S. Pat. No. 5,138,344 to Ujita, entitled xe2x80x9cInk Jet Apparatus and Ink Jet Cartridge Therefor.xe2x80x9d This patent indicates that an ink-containing replaceable reservoir can be provided with an integral information device (i.e., a resistor element, magnetic medium, bar code, integrated circuit or ROM), for storage of information relating to control parameters for an ink jet printer.
Accordingly it is an object of this invention to provide a method and apparatus for purging old ink from an ink delivery system in a printer and recharging the ink delivery system with new ink.
A method and apparatus are disclosed for purging a tube in an ink delivery system in a printer, where a purging fluid is introduced into the inlet end of the tube. The printhead of the ink delivery system is operated to cause the purging fluid to flow through the tube and be expelled by the printhead, and the purging fluid is collected.
A purging reservoir, a purging printhead, and a purging printhead cleaning device are provided for use in an ink jet printer having a replaceable ink reservoir, a replaceable printhead and a replaceable printhead cleaning device. The purging reservoir, purging printhead, and purging printhead cleaning device are installed in place of the respective replaceable printing components. The purging reservoir contains a purging solution for cleaning ink from the tubing in the printer which connects the reservoir with the printhead. Upon installation, a processor in the printer recognizes the purging printing components and initiates a purging procedure, cleaning old ink from the tubing and charging the tubing with new ink.
The purging reservoir, purging printhead, and purging printhead cleaning device may be incorporated into a kit.
The kit may also include a computer storage medium containing a program for use by a processor in the printer wherein the processor operates to control the purging procedure in accordance with the program.